Intraguild predation and cannibalism between two co-occurring ladybird species (Coccinella septempunctata and Menochilus sexmaculatus): A fight for supremacy

Abstract

Coccinella septempunctata L. (C7) and Menochilus sexmaculatus (Fabricius) (Ms) are aphidophagous ladybirds (Coleoptera: Coccinellidae), which dominates the ladybird fauna of Oriental region. Since these species co-occur and are highly predaceous on various aphids, it was hypothesized that in the scarcity or absence of aphids, i.e., extraguild prey, one ladybird species will start attacking and killing the other one, which will endanger their co-occurrence. Thus, we aim to determine, which ladybirds’ larvae will subdue the other; their attack rates (rate at which a superior individual attacks the inferior one), escape rates (rate at which an inferior individual escapes from the attack of superior one) and predation rates (rate at which a superior individual eats the inferior one) were investigated, as they indulged in cannibalism and intraguild predation. Larvae of C7 were slightly bigger and heavier than those of Ms, thereby they gained a slight competitive advantage. This enabled C7 a better attacker and an escapist when confronted with larvae of Ms in a predatory guild, which resulted in lesser larval mortality due to intraguild predation by Ms larvae. However, C7 successfully preyed upon the larvae of Ms. The highest rate of cannibalism and intraguild predation was executed by C7 which made it a potent cannibal and an intraguild predator. Despite being outplayed by C7, the inferior Ms larvae didn’t suffer much loss during the intraguild combat due to their armoured morphological features in the form of spines and rough texture. This is the reason why Ms still exists as the second most commonly occurring ladybird in the field.